Kosovo is slouching toward independence - a formal declaration may come before the end of the month - and that's going to require diplomatic attention and cool judgment on the part of the United States and its European allies.
Kosovo, once independent, could explode (and set off a detonation in nearby Bosnia among ethnic Serbs there), but this is by no means inevitable. What is more likely to happen is that the Serbs in Kosovo's northern slice, already essentially run by Serbia, will reinforce their links to Belgrade. Serbs elsewhere in Kosovo are more of a question mark, but if they're not provoked by the Kosovar Albanians, they'll probably grumble and do nothing.
This is where the foreign military presence comes in: In declaring legal independence from Serbia, Kosovo will still be a long way from declaring practical independence from NATO, which has 15,000 troops there. NATO commanders will be expected to deploy their forces wisely and in a way that inhibits free-lance violence by Serbs or, more to the point, Kosovar Albanians.
The institutional development of Kosovo is still pretty thin, ensuring a continuing foreign presence in administration, as well. Russia's opposition to an independent Kosovo will hamper the role of the United Nations, but members of the European Union can help fill the gaps. For years, the West hoped to bring Russia around on this issue; it can't, and that's just going to have to be a fact of Balkan life.
The impact of an independence declaration may be bigger in Serbia than in Kosovo itself. Serbia's founding legend is tied up with Kosovo, and it was with the invocation of that legend that Serbia launched its bloody assault on the Kosovar Albanians in 1999. Serbia's politicians may react demonstratively to Western acceptance of an independent Kosovo; Belgrade may try to stir up trouble and at the same time turn inward.
But this may be the shock that Serbia needs, and, given time, a new generation of more realistic political leaders could emerge there. Polls suggest that ordinary Serbs just wish the Kosovo issue would go away; a formal break, painful as it might seem to them, may be the best way to make that happen.